Digital PLL Auto-Calibration for Frequency Drift Locking
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Solution Overview
Problem
Conventional phase-locked circuits lack an automatic calibration function, leading to inefficient frequency calibration due to frequency drift caused by environmental factors, requiring additional equipment and increasing costs with higher resolution demands.
Innovation Solution
A digital phase-locked loop with an automatic calibration function, comprising a frequency and phase locked circuit, calibration circuit, oscillator circuit, divider, and frequency and phase detector, which automatically calibrates frequency drift by tracking and locking calibrated frequencies and phases within defined ranges, eliminating the need for external calibration devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional phase-locked circuit is used without automatic calibration function, then device complexity is reduced, but frequency calibration efficiency deteriorates and additional equipment is required
Solution Approach 1:
The patent merges the calibration function with the frequency-locked loop circuit by integrating a calibration circuit that stores calibration data into the existing circuit architecture. The frequency-locked loop circuit performs both frequency locking and automatic calibration functions, eliminating the need for separate external calibration equipment while maintaining automated operation.
Solution Approach 2:
The calibration circuit enables the frequency-locked loop circuit to perform self-calibration by automatically detecting frequency drift and applying corrections using stored calibration data. The system calibrates itself without external intervention, improving automation while keeping the added complexity minimal through reuse of existing circuit resources.
2Measurement precision
If higher resolution is required for frequency calibration, then measurement precision is improved, but the number of control bits increases resulting in higher cost
Solution Approach 1:
The calibration circuit pre-stores calibration data corresponding to different frequency drift conditions in a lookup table format. When frequency drift occurs, the system quickly retrieves the appropriate calibration parameters from pre-computed data rather than calculating them in real-time, achieving high precision calibration with minimal control bits and reduced computational complexity.
3Reliability
If additional equipment is used for frequency calibration, then calibration accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The frequency-locked loop circuit is designed to perform multiple functions: frequency locking, phase locking, and automatic calibration. The same circuit components are reused for different purposes, eliminating the need for dedicated external calibration equipment while maintaining calibration accuracy through intelligent control algorithms and pre-stored calibration data.
Data Source
AI summary
A digital phase-locked loop with an automatic calibration function and an automatic calibration method thereof are provided. The digital phase-locked loop includes a frequency and phase detector, a calibration circuit, a frequency and phase locked circuit, and an oscillator circuit. The frequency and phase locked circuit outputs an initial control signal. The calibration circuit calibrates an initial frequency and outputs an initial calibration signal having a calibrated initial frequency when determining that the initial frequency does not fall within an allowable error calibration range. The frequency and phase locked circuit locks the calibrated initial frequency when determining that the calibrated initial frequency falls within a locked frequency range. The oscillator circuit outputs an oscillator signal according to the initial calibration signal and the initial control signal. Therefore, a resolution of the oscillator circuit can be improved by the automatic calibration of frequency drift caused by processes and environments.